I don't make this stuff up folks. I am weary of hearing about things like trunk leaks and door hinges..........so lets open another discussion. I noticed that when I rolled backwards down a hill and applied the brakes, the feel was entirely different and the pedal had to be depressed much harder to stop. This was when I still had drum brakes and I am aware that the leading -trailing shoe issue in drums may come into play here. I have since converted to disc and noticed the same thing. One would think that when the caliper pistons clamp down on the disc, it would not matter which direction the rotor was turning, but obvioulsy it does. These are 4-pot calipers and the brakes will slide the wheels on any pavement at any forward speed. These are the rears I am talking about. The fronts are single pots and they work about as well going in either direction. I am not a "brakespert" and there may be a scientific explanation for this. Could it be some difference in the load shift? When you brake going forward you shift all the load to the front and away from the rear. Going backwards, you shift all the weight to the rear and into the brakes.
Somebody go outside, coast down a hill backwards, jam on your rear brakes and tell me if they work as well going in the wrong direction.